[Idiopathic hypokalemic periodic paralysis presenting peculiar insulin secretion]

A 24-year-old male was admitted to our hospital because of the paralytic attack. He was well until he went to bed the day before, and he found his limbs unmovable in the morning. The initial attack occurred at age 11 and subsequently he had two episodes of the reversible generalized weakness which always appeared in the morning and continued for about one day at age 14 and 21, respectively. The provocative factors were uncertain. There was no family history of paralytic attacks nor thyroid diseases. On the neurologic examination he presented flaccid tetraparesis without the facial and respiratory involvements. The laboratory studies showed that the serum potassium was 2.4 mEq/l and the thyroid function was normal. The oral and intravenous potassium chloride was given and within two days the serum potassium turned back to the normal level, and he has recovered completely from the paralysis. An oral 75g glucose load was performed. The serum immunoreactive insulin (IRI) was elevated from the basal level to 289 microU/l, showing the prominent peak response at 30 min after the load, and both the serum potassium and the grasping power decreased significantly, although the blood glucose fluctuated within the normal level. After the prophylactic treatment with acetazolamide 2,000 mg daily for 7 days, this markedly elevated initial insulin response has disappeared and moreover the weakness of grip was milder, however, the serum potassium decreased notedly. This case revealed that in the idiopathic hypokalemic periodic paralysis the attack was possibly induced by the extraordinarily secreted insulin which was supported by the acetazolamide treatment.